Gripper for dowel machines



Oct. l0, 1950 M. DEsPREs 2,525,118

' GRIPPER FOR no wEL MAcHImzs Filed nay 12., 194'? m m Q09/3 A PatentedOct. 10, 1950 UNITED -f STATES PATENT OFFICE GRIPPER FOR DOWEL MACHINESMarcel Despre's, Grand RapidarMich.` Application May 12, 1947, SerialNo. 747,569 l (ol. 142-54) 1 claim.

i"'Dhisfinvention` is directed. to a novel feeding gripper for engaging,gripping and periodically feding dowel rods of required lengths, a dowelbeing cut from the `rod between successive feed-y ing movements thereof.

The dowel rods used are` continuously helically grooved around theirouter surfaces, the distancebetween succeeding grooves` in the length`cf the rod being small. The gripper` which I have provided insurescertainity inlfeeding the dowel rod without lost motion, and with littleor no penetrationV at the surface of the rod by the pointedV ends of thefeeding members used. y Y

It is,l an object and purpose of the present invention to provide animprovement in dowel rod feeding by gripping engagement thereof by anovel gripper structure which is more certain and accurate inA operationthan previously used.

i.; Anunderstanding of the invention may be had Fig. 3 is a fragmentaryvertical transverse section of the structure in Fig. 2, lookingthereagainst from the left,

Fig. 4 is a fragmentary, further enlarged, elevation better showing thespacing or separation of the gripper fingers at their pointed ends wherethey bear against the surface of a dowel rod,

Fig. 5 is a fragmentary plan view showing a slight codification instructure from that shown in Figs. 1, 2, and 3, and

Fig. 6 is a vertical section and elevation on the plane of line Gti- 5of Fig. 5, looking in the direction indicated.

Like reference characters refer to like parts in the different figuresof the drawing.

For so much of the dowel machine as is required to show the environmentof the invention, spaced vertical supports I, with suitable bearings 2passing therethrough, carry a somewhat elongated tubular shaft 3 whichextends through the bearings and is rotatably mounted therein. The shaftmay be driven by a belt pulley 4 thereon, around which a drive belt isplaced. One end of the tubular shaft 3 has an outwardly taperingenlargement of the cylindrical passage therethrough, as shown in Fig. 1.

A tube il extends lengthwise of the shaft 3 but is shorter than theshaft. At its end nearest the tapered seat in the shaft 3 described, adowel rod holding head t is connected, preferably by 'threading`thereon. The head is radially split at several spaced .places at itsouter portion, and has outwardly inclined sides complementary to thetapered conical seat in the adjacent end of the shaft 3.,' At theopposite end a head l, having an annular iiange at its outer end,isscrew connected to the rodl 5. A collar 8l between the tube 5 and theshaft 3 is pinned to the shaft and between it and the outer end of themember l, a coiled compression spring 9 is located, the normal action ofwhich is to move the tube 5 to the right and close the jaws of the headV.6 against a dowel rod passing therethrough.

In the, operation of the machine, a ypressure head It which has acentral opening through which the dowel rod EI passes, the member l andthe head 6 also having axial openings for such passage of the rod, ismoved against the flange of the member l, compressing the spring 9 andmoving the rod 5 and the head 6 longitudinally for release of the clampmade by the head t upon the rod II. The dowel rod II of the regularlength used at its outer surface is grooved with a shallow groove of acontinuous helical form as shown. It is during the time that the head 6releases the rod II that it is fed lengthwise beyond said head for thenext succeeding transverse cut therethrough, to make a dowel of therequired length, and the cutting transversely occurs when the rod isclamped and held securely against movement by the closing of the jaws ofthe head 6 thereagainst.

On the shaft 3 between the supports I, a collar I2 is slidably mountedand keyed to the shaft to turn therewith. In the machine operation, inaccordance with regular practice, the collar I2 is moved back and forthon the shaft 3 in proper timing with the clamping and releasing of therod I l by the head 6, through the actuation of a yoke I3 associatedwith the collar, the detail of which is old. The collar I2 carries twodiametrically opposed series of dowel engaging fingers I4. The iingersI4, as best shown in Fig. 2, are pivotally mounted side by side, betweentheir ends, on a pivot pin I5, which passes through arms or brackets I6extending from the collar I2. The shaft I3 and the tube I5 are slottedfor a distance suicient for the fingers at their inner end portions topass through said slots and move back and forth longitudinally of BJ theshaft with the movement of the collar I3. It will be noted that of thethree gripper ngers I4 (Fig. 4) they are disposed to bear against thedowel rod I I in spaced relationship to each other in the direction ofthe length of the rod, so that in any case, one of the pointed ends of afinger will be very close to the helical groove in the rod, so that whenthe collar and fingers have been moved to the right and the pointed endsof the fingers have slid over the rod at op-positesides thereof, on thereturn movement to the left, a finger will engage in a groovesubstantially instantaneously and there will be no lost movement of thefingers over the rod in the direction of feeding which, if all of thepointed ends of the iingers were located in the same position,

might require movement a distance between successive spirals of thegroove before engaging therewith.

The upper end portions of the ngers I4 pass through opposed slots at theupper end of a sleeve I'I carried on the collar I2, and within a crosspin I8 at the outer end of the sleeve I'I. Between the collar I2 whichprovides a bottom at the inner end of the sleeve I'I and the inner edgesof the iingers, a coiled compression spring I9 is located. The outsideiingers 0f a series, three being in a series as shown, terminate in armslila and the middle or intermediate finger at its upper end terminatesin an arm Mb (Fig. 2) crossing the arms Illa, so that opposite sides ofthe upper coil of the spring I9 come against the inner edges of the armsIlia and Mb, 'respectively, getting a better spring pressure engagement.

In Fig. 5, instead of a single sleeve I I and a single spring I9 foreach of the series of three of the gripping and feeding ngers, three ofsuch sleeves are used, one for each of the fingers I4, and each having aspring I9 therein. Each of the sleeves is slotted at its outer endportion and the side fingers are laterally oiset to reach theirrespective sleeves and springs, as shown in Figs. 5 and 6. Otherwise,the construction is the same and operates in the same manner.

With the structure described, the gripping of the dowel rod for feedingpurposes is better and more surely attained than heretofore. There is vapositive gripping and feeding of the rod without the dangers and chancesof undesired move- 4 ment of the gripping lingers without anaccompanying movement of the rod when the ngers are moved in thedirection of outward feeding. And at the same time, the lingers may bemoved in reverse to engage the rod at a place farther back for the nextsucceeding feeding movement, the pointed ends of the fingers movingfreely over the opposed surfaces of the rod.

While the rngers in the groove are shown as three in number, such numbermay be varied if desired. Similarly, while two series are showndiametrically opposed to each other in Fig. 1, the invention is notnecessarily limited to two 'series of such' multiple iingers, but agreater number of such series of fingers may be used.

The invention is dened in the appended claim, and is to be consideredcomprehensive of all forms of structure coming within its scope.

I claim:

The combination with a dowel machine having guide means for a dowel rodand a carriage mounted for reciprocatory movement in the direction ofthe length of the dowel rod, of means to grip the dowel rod comprising aplurality of gripping ngers pivotally mounted on the carriage adjacenteach other intermediate their ends, said fingers having ends ofdifferent lengths extending into engagement with the dowel rod, a singlecoiled spring mounted on the carriage, said iingers having other endsextending adjacent an end of said spring and being shaped to engage theend of the spring at substantially diametrically opposite pointsthereof, and means for guiding said spring and said other ends of thelingers.

MARCEL DESPRES.

REFERENCES CITED l The following references are of record in the

